This research project is designed to increase our understanding of the internal mechanisms of the reaction time (RT) response generation and to use this information toward more precise diagnostic procedures for distinguishing three clinical groups of aging patients, i.e., depression, senile dementia and normal aged. The goal for the current year was to develop the technology required for microbehavioral analysis of the RT response and to commence the data collection stage of the project. Twenty-four subjects have been tested to this date: four patients with senile dementia, two with organic brain syndrome, four depressives and fourteen normal (ten old and four young) control subjects. Numerous aspects of the psychomotor slowing can be distinguished at several different points along the response curve. The RT response itself provides, particularly in senile dementia patients, a rather complex picture of force distributions. Responses to stimuli constituting the memory function items clearly indicate not only effects of memory on the RT "saving" due to repeated presentations, but also suggest some changes in the functional characteristics of responses as well. This study has significant implications for both theoretical and clinical areas of psychophysiological research. On one hand, it will provide a far more detailed picture of information processing and psychomotor capabilities of the individual tested than any of the techniques presently used. On the other hand, although the present study tests the microbehavioral approach on three very common clinical groups of aged patients, the precise information on psychomotor decrements is just as relevant to many other clinical populations, such as mentally retarded, schizophrenics, brain damaged and so on.